A typical commercial exhaust hood system requires a large amount of energy to run, including energy used to heat, cool and/or dehumidify air removed from the cooking environment, as well as energy used by the fans to put air into the room and remove it. Commercial hood systems are designed to meet the demands of all of the cooking equipment operating at full load, but in reality there are many times when the cooking equipment is operating at less than full load and even some times when certain cooking equipment may not be on at all. In such cases the hood exhaust systems can be slowed down, saving heating, cooling and fan energy consumed.
Systems have been developed in the past to account for these issues. Commonly such systems utilize a temperature sensor in the exhaust duct leading from a hood canopy, and this temperature is used to set fan speed. However, this duct temperature represents the overall average temperature of the system. In reality, not all cooking devices contribute the same amount of heat load. To account for this other systems have been considered that utilize optics, infrared or other means to identify conditions for control of the fan.
Still other systems have been developed in which a plurality of temperature sensors mounted within the hood canopy and spaced apart along a width of the hood canopy are provided for sensing temperatures at respective locations within the hood canopy. The system monitors actual temperature at each location as indicated by the temperature sensors and responsively controlling the fan based upon the monitoring. In particular, each temperature sensor location has am associated rated fan triggering temperature field, and fan speed is controlled based upon the actual temperature at the location having the highest loading of its rated fan triggering temperature field.
It would be desirable to provide a system and method that enhances the overall operation and performance of such ventilation systems.